Spatial Scaling Analyses of Soil Physical Properties: A Review of Spectral and Wavelet Methods

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Understanding the scaling properties of soil spatial variability is important for managing natural resources and protecting our environment. Our objective was to present methodology that has been used or has the potential to be used in spatial scaling of soil properties. The spectral and wavelet analyses were presented and illustrated using the soil hydraulic conductivity and other basic soil physical properties collected along a transect in Saskatchewan, Canada. We introduced periodogram, spectral analysis, simple squared coherency, and multiple coherency analyses as the frequency domain tools. For the wavelet analysis, the wavelet transform, cross wavelet spectrum, and simple wavelet coherency analysis were introduced. Detailed procedures and precautions for these analyses were also presented. The significance tests for different analyses were discussed and multiple testing for the wavelet analysis was introduced.